introducing bytes methods for AbstractStringAssert

Fix #3232

assertj-core/src/main/java/org/assertj/core/api/AbstractStringAssert.java

@@ -22,6 +22,8 @@
 import static org.assertj.core.error.ShouldBeNumeric.NumericType.LONG;
 import static org.assertj.core.error.ShouldBeNumeric.NumericType.SHORT;
 
+import java.io.UnsupportedEncodingException;
+import java.nio.charset.Charset;
 import java.util.Base64;
 import java.util.Comparator;
 
@@ -459,6 +461,76 @@ public AbstractByteAssert<?> asByte() {
     }
   }
 
+  /**
+   * Encodes the actual value as byte array using the platform's default charset, the encoded byte array becoming the new value under test.
+   * <p>
+   * Examples:
+   * <pre><code class='java'> assertThat("abc").bytes()
+   *                  .isEqualTo(new byte[] {'a', 'b', 'c'});
+   *
+   * assertThat("").bytes()
+   *               .isEmpty(); </code></pre>
+   *
+   * @return a new {@link AbstractByteArrayAssert} instance whose value under test is the result of parsing the string.
+   * @throws AssertionError if the actual string is {@code null}.
+   *
+   * @since 3.26.0
+   */
+  public AbstractByteArrayAssert<?> bytes() {
+    isNotNull();
+    return InstanceOfAssertFactories.BYTE_ARRAY.createAssert(actual.getBytes()).withAssertionState(myself);
+  }
+
+  /**
+   * Encodes the actual value as byte array using a specific {@link Charset}, the encoded byte array becoming the new value under test.
+   * <p>
+   * Examples:
+   * <pre><code class='java'> assertThat("abc").bytes(StandardCharsets.US_ASCII)
+   *                  .isEqualTo("abc".getBytes(StandardCharsets.US_ASCII));
+   * 
+   * assertThat("").bytes(StandardCharsets.US_ASCII)
+   *               .isEmpty(); </code></pre>
+   *
+   * @param charset the {@link Charset} to be used to encode the string.
+   * @return a new {@link AbstractByteArrayAssert} instance whose value under test is the result of parsing the string.
+   * @throws NullPointerException if charset parameter is {@code null}.
+   * @throws AssertionError if the actual string is {@code null}.
+   *
+   * @since 3.26.0
+   */
+  public AbstractByteArrayAssert<?> bytes(Charset charset) {
+    isNotNull();
+    byte[] bytes = actual.getBytes(requireNonNull(charset, "The charset must not be null"));
+    return InstanceOfAssertFactories.BYTE_ARRAY.createAssert(bytes).withAssertionState(myself);
+  }
+
+  /**
+   * Encodes the actual value as byte array using a specific {@link Charset}, the encoded byte array becoming the new value under test.
+   * <p>
+   * Examples:
+   * <pre><code class='java'> assertThat("abc").bytes(StandardCharsets.US_ASCII)
+   *                  .isEqualTo("abc".getBytes(StandardCharsets.US_ASCII));
+   *
+   * assertThat("").bytes(StandardCharsets.US_ASCII)
+   *               .isEmpty(); </code></pre>
+   *
+   * @param charsetName the Charset to be used to encode the string.
+   * @return a new {@link AbstractByteArrayAssert} instance whose value under test is the result of parsing the string.
+   * @throws NullPointerException if named charset parameter is {@code null}.
+   * @throws AssertionError if the actual string is {@code null} or if the named charset parameter is not supported.
+   *
+   * @since 3.26.0
+   */
+  public AbstractByteArrayAssert<?> bytes(String charsetName) {
+    isNotNull();
+    try {
+      byte[] bytes = actual.getBytes(requireNonNull(charsetName, "The charsetName must not be null"));
+      return InstanceOfAssertFactories.BYTE_ARRAY.createAssert(bytes).withAssertionState(myself);
+    } catch (UnsupportedEncodingException e) {
+      throw failures.failure(charsetName + " is not a supported Charset");
+    }
+  }
+
   /**
    * Parses the actual value as short, using radix 10, the parsed short becoming the new value under test.
    * <p>

assertj-core/src/test/java/org/assertj/core/api/string_/StringAssert_bytes_Test.java

@@ -0,0 +1,167 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ *
+ * Copyright 2012-2024 the original author or authors.
+ */
+package org.assertj.core.api.string_;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatNullPointerException;
+import static org.assertj.core.api.BDDAssertions.then;
+import static org.assertj.core.util.AssertionsUtil.expectAssertionError;
+import static org.assertj.core.util.FailureMessages.actualIsNull;
+import static org.junit.jupiter.params.provider.Arguments.arguments;
+
+import java.io.UnsupportedEncodingException;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+import java.util.stream.Stream;
+
+import org.assertj.core.api.StringAssert;
+import org.assertj.core.api.StringAssertBaseTest;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+/**
+ * @author Emanuel Trandafir
+ */
+class StringAssert_bytes_Test extends StringAssertBaseTest {
+
+  @Override
+  protected StringAssert invoke_api_method() {
+    // Tested below.
+    return null;
+  }
+
+  @Override
+  protected void verify_internal_effects() {
+    // Verify disabled as the bytes() cast have no internal effect.
+  }
+
+  @Override
+  public void should_return_this() {
+    // Test disabled as the assertion does not return this.
+  }
+
+  @ParameterizedTest
+  @MethodSource
+  void should_encode_string_to_byte_array_according_to_the_default_charset(String actualString, byte[] expectedBytes) {
+    assertThat(actualString).bytes()
+                            .isEqualTo(expectedBytes);
+  }
+
+  static Stream<Arguments> should_encode_string_to_byte_array_according_to_the_default_charset() {
+    return Stream.of(arguments("abc", new byte[] { 'a', 'b', 'c' }),
+                     arguments("ABC", new byte[] { 'A', 'B', 'C' }),
+                     arguments("&%ç", "&%ç".getBytes()));
+  }
+
+  @ParameterizedTest
+  @MethodSource
+  void should_encode_string_to_byte_array_according_to_the_given_charset(String actualString, byte[] expectedBytes,
+                                                                         String charset) {
+    assertThat(actualString).bytes(charset)
+                            .isEqualTo(expectedBytes);
+  }
+
+  static Stream<Arguments> should_encode_string_to_byte_array_according_to_the_given_charset() throws UnsupportedEncodingException {
+    return Stream.of(arguments("abc", new byte[] { 'a', 'b', 'c' }, "windows-1254"),
+                     arguments("çüş", "çüş".getBytes("windows-1254"), "windows-1254"));
+  }
+
+  @Test
+  void should_not_throw_exception_for_empty_string() {
+    assertThat("").bytes().isEmpty();
+  }
+
+  @Test
+  void should_throw_assertion_error_for_null_input() {
+    // WHEN
+    AssertionError assertionError = expectAssertionError(assertThat((String) null)::bytes);
+    // THEN
+    then(assertionError).hasMessage(actualIsNull());
+  }
+
+  @Test
+  void should_encode_string_to_byte_array_for_specific_charset_and_valid_input() {
+    // GIVEN
+    String actual = "abc";
+    // WHEN/THEN
+    then(actual).bytes(StandardCharsets.US_ASCII)
+                .isEqualTo(actual.getBytes(StandardCharsets.US_ASCII));
+  }
+
+  @Test
+  void should_not_throw_exception_for_specific_charset_and_empty_string() {
+    // GIVEN
+    String actual = "";
+    // WHEN/THEN
+    then(actual).bytes(StandardCharsets.US_ASCII).isEmpty();
+  }
+
+  @Test
+  void should_throw_assertion_error_for_specific_charset_and_null_input() {
+    // GIVEN
+    String actual = null;
+    // WHEN
+    AssertionError assertionError = expectAssertionError(() -> assertThat(actual).bytes(StandardCharsets.US_ASCII));
+    // THEN
+    then(assertionError).hasMessage(actualIsNull());
+  }
+
+  @Test
+  void should_throw_exception_for_null_charset() {
+    assertThatNullPointerException().isThrownBy(() -> assertThat("abc").bytes((Charset) null))
+                                    .withMessage("The charset must not be null");
+  }
+
+  @Test
+  void should_encode_string_to_byte_array_for_specific_charset_name_and_valid_input() {
+    // GIVEN
+    String actual = "abc";
+    // WHEN/THEN
+    then(actual).bytes("UTF-8").isEqualTo(actual.getBytes(StandardCharsets.UTF_8));
+  }
+
+  @Test
+  void should_not_throw_exception_for_specific_charset_name_and_empty_string() {
+    // GIVEN
+    String actual = "";
+    // WHEN/THEN
+    then(actual).bytes("UTF-8").isEmpty();
+  }
+
+  @Test
+  void should_throw_assertion_error_for_specific_charset_name_and_null_input() {
+    // GIVEN
+    String actual = null;
+    // WHEN
+    AssertionError assertionError = expectAssertionError(() -> assertThat(actual).bytes("UTF-8"));
+    // THEN
+    then(assertionError).hasMessage(actualIsNull());
+  }
+
+  @Test
+  void should_throw_exception_for_null_charset_name() {
+    assertThatNullPointerException().isThrownBy(() -> assertThat("abc").bytes((String) null))
+                                    .withMessage("The charsetName must not be null");
+  }
+
+  @Test
+  void should_throw_AssertionError_for_invalid_charset_name() {
+    // WHEN
+    AssertionError assertionError = expectAssertionError(() -> assertThat("abc").bytes("UNSUPPORTED_CHARSET"));
+    // THEN
+    then(assertionError).hasMessage("UNSUPPORTED_CHARSET is not a supported Charset");
+  }
+
+}